1. Field of the Invention
The present invention relates to a transfer printer in which paper is inserted between a printing head and a platen and printing is performed on the paper with the printing head by using an ink ribbon.
2. Description of the Related Art
As a transfer printer of this type, for example, U.S. Pat. No. 5,106,215 discloses a printer which has an ink ribbon magazine detachably fitted to the printer body and which performs printing with a thermal head by using an ink ribbon withdrawn from the magazine.
An ink ribbon magazine has a pair of side plates coupled to each other to oppose each other, a supply reel and a take-up reel rotatably supported between these side plates, and a plurality of guide rollers. The unused portion of an ink ribbon is wound on the supply reel in a roll manner, and the portion of the ink ribbon used for printing is taken up by the take-up reel.
The printer body incorporates a printing portion having a thermal head and a platen roller opposing the thermal head, a support arm for supporting the ribbon magazine, a ribbon driving mechanism for driving the supply reel and take-up reel of the ribbon magazine, a pair of parallel support frames supporting the printing portion, the support arm, and the ribbon driving mechanism, and the like.
In order to facilitate mounting and removal of the ink ribbon magazine on and from the printer body, the thermal head and the support arm are cantilevered by one support frame. More specifically, each of the thermal head and the support arm has one end fixed to one support frame, and a non-held free end located adjacent to the other support frame. In mounting, the ink ribbon magazine is inserted in the printer body from the free end side of the support arm and mounted on the support arm, and is coupled to the ribbon driving mechanism provided on one support frame. At this time, the ink ribbon of the ink ribbon magazine is inserted between the thermal head and the platen roller from the free end side of the thermal head.
A support plate is pivotally mounted on the other support frame. After the ink ribbon magazine is mounted in the printer body, this support plate is pivoted to become parallel to one support frame and is engaged with the free ends of the support arm and thermal head, thereby supporting these free ends. Thus, each of the support arm and the thermal head is pseudo-supported at its two ends by one support frame and the pivotal support plate.
In the transfer printer, when the platen roller and the thermal head have small widths (in a direction perpendicular to the paper convey direction), the parallel degree between the platen roller, the thermal head, and the ink ribbon supplied from the ink ribbon magazine is not so decreased as to pose a problem. For this reason, even if the thermal head and the ink ribbon magazine are cantilevered, printing quality is no so degraded. When, however, the platen roller and the thermal head have lengths of about 100 mm (abut 4 inch), with the cantilever structure, the parallel degree between the platen roller, the thermal head, and the ink ribbon is largely impaired. Therefore, a degradation in printing quality becomes large, leading to a problem.
As described above, when a pivotal support plate is provided at the support frame of the printer body and the thermal head and the ribbon magazine are supported at their two ends, the parallel degree can be maintained. With this arrangement, however, the support plate must be pivoted when mounting and removing the ink ribbon magazine, degrading the operability. Since the pivotal support plate is provided, the number of components is increased and the arrangement becomes complicated.